Yes, I will look at this bug! It’s weird, the shaders were not changed, and this texture also fails even when the old pk3 is alongside the new one so it’s not a missing file. I see no reason for that bug currently, that’s interesting.
Note that 11 years ago not putting the .map file alongside the .bsp was a possible trick to save file space in .pk3, but with today’s computers, network, and modern client which are able to download efficiently, putting the .map file in .pk3 is the best way to not lose sources. As Linus said one day, “Backups are for wimps. Real men upload their data to an FTP site and have everyone else mirror it.”
Some original tremulous maps weren’t shipped with .map file and they are now a pain to maintain. One day I asked Stannum for his transit map and even himself was not able to find something good, the only one .map file he founds was a one named final but appeared to be an intermediary version between Tremulous 1.0.2 and Tremulous 1.1.0, and some required mapmodels (like escalator stair) were missing of course. Which is so bad since Transit is the original Tremulous map with the worst lightmaps, but no one can recompile them… If I were id Software 20 years ago, I would design q3map2 to embed the source in one dedicated bsp lump by default to prevent source losing. Distributing map sources looked to not have been a problem for them since they did it with Doom3 lately, just the .bsp format not required it.
There are some practical downsides for the purpose of current backwards compatibility in trem (in particular related to supporting the 1.1 vanilla stock client from trem.net which unfortunately many people still use). The 1.1 stock client can only download directly from the game server, although thanks to an improvement to the game server by @DevHC, the newest multiprotocol trem servers can offer download usually around 100kb/s and beats the old 3 kb/s (which even gpp had, but everyone used the web downloads, so it was hardly ever noticed).
The other issue is an old bug in the game servers that hasn’t been fixed yet where the downloads of pk3 files over 32 MB freezes at 32 MB. Again, with the web downloads, this bug was never really a noticable issue for clients and server that used web downloads, but for the 1.1 vanilla stock clients, and servers that want to still support them it is.
These are just some factoids to consider, there are many maps that include .map files that are still manageable for backwards compatibility. In the case of this version of pulse, the size of the most recent pk3 file without a .map is 21.7 MB, the size of the .map (uncompressed) is 8.4 MB, so the resulting pk3 would be X amount less than 30.1 MB, which is still under 32 MB, so it would still work.
More players are upgrading to the 1.3 alpha client ( found here: https://github.com/GrangerHub/tremulous/releases ), and many of them were using the 1.1 vanilla stock client right before, so hopefully at some point enough people will be upgrading where the above mentioned issues will become moot. But yes, keeping the .map in the map pk3 is definitely good practice in general.